Sure thing! We've got 741 and we're gonna multiply it by 21. That's the same as adding 741 to itself 21 times.
Step 1: 0 + 741 = 741
Step 2: 741 + 741 = 1482
Step 3: 1482 + 741 = 2223
Step 4: 2223 + 741 = 2964
Step 5: 2964 + 741 = 3705
Step 6: 3705 + 741 = 4446
Step 7: 4446 + 741 = 5187
Step 8: 5187 + 741 = 5928
Step 9: 5928 + 741 = 6669
Step 10: 6669 + 741 = 7410
Step 11: 7410 + 741 = 8151
Step 12: 8151 + 741 = 8892
Step 13: 8892 + 741 = 9633
Step 14: 9633 + 741 = 10374
Step 15: 10374 + 741 = 11115
Step 16: 11115 + 741 = 11856
Step 17: 11856 + 741 = 12597
Step 18: 12597 + 741 = 13338
Step 19: 13338 + 741 = 14079
Step 20: 14079 + 741 = 14820
Step 21: 14820 + 741 = 15561

So, 741*21 = 15561